Hydraulic system problems ('85 5000 turbo)

Ameer Antar antar at comcast.net
Fri Aug 18 11:16:49 EDT 2006

Thanks for everyone's  help on this problem.Well, I tried bleeding the system last night, but it only made a minor improvement. I was turning the steering wheel back and forth for almost 20 minutes with the help of my brother. I also cracked open the pressure lines on the pump and saw a decent amount of fluid come out. I tested the servo w/ the procedure below. Only a small amount of fluid came out of the line with the engine off, then it stopped. With the engine running, almost nothing came out, so seems like the servo is OK.
The fluid level still goes down from the max to min points on the reservoir. This seems like too much, but I cant remember how it used to work. I am getting a warning from the check system at about 2 minutes after starting the engine cold. Then it goes away. Does that mean anything to anyone?
The only other weak point I can think of is the brake accumulator; this was a rebuilt one. Could this be causing these symptoms? Any more advice or diagnosis procedures is much appreciated.
-------------------- Original Message --------------------
From:Fred Munro [munrof at sympatico.ca]
To:Ameer Antar [antar at comcast.net], Quattro List [quattro at audifans.com]
Date:8/17/06 5:23:31 PM
Subject:RE: Hydraulic system problems ('85 5000 turbo)

You may have a bad brake servo. When you run the engine, the brake bomb is
charged and the reservoir level goes down. When you stop the engine, the
pressurized bomb discharges through the leaking servo into the reservoir and
the level goes up. A badly leaking servo will prevent enough pressure from
building up in the system to provide brake boost - the fluid recirculates
from the pump through the leaking servo back into the reservoir.

There is a standard test for the servo, but the test is not effective if it
is leaking so badly that the bomb discharges rapidly . To test a servo with
a bad leak, remove the return hose from the servo to the reservoir and pinch
it closed. Attach a hose from the servo return and lead it into a bottle.
Start the engine. DO NOT APPLY THE BRAKES! If the servo is bad, oil will be
flowing into the bottle. If it is good, no oil will be coming out of the
hose. NOTE: Make SURE you remove the RETURN hose, NOT the FEED hose from the

This is based on my fading recollection of the Type 44 hydraulics. I just
went through this with my UrS6 and FWIR the systems are fairly similar in


Fred Munro
'94 S4
'97 S6

-----Original Message-----
From: quattro-bounces at audifans.com
[mailto:quattro-bounces at audifans.com]On Behalf Of Ameer Antar
Sent: August 17, 2006 10:56 AM
To: Quattro List
Subject: Hydraulic system problems ('85 5000 turbo)
All, I'm having a major problem with the hydraulic system on my 5000
turbo. Hopefully someone can help. I've replaced pretty much every
component in the system, including the rack, pump, accumulator (bomb),
reservoir, all hoses/lines and fittings. The accumulator is one of those
recharged bombs. The only piece I havn't changed is the brake servo. The
problem is after replacing all that, there's still almost no power
steering or brakes. The power assist does seem to randomly change. Some
times I can feel a little assist, but for the most part there's pretty
much nothing. Since there's no power steering or brake, I'm thinking
it's got to be something up with the pump or upstream of that... Any
ways to do diagnosis?
Also, I noticed that the fluid level in the reservoir changes a lot. When
the car is off, it's right about at the max, and when running it's
very close to the minimum. Is that normal? I'm pretty sure I used the
right banjo bolts b/c this system uses crush washers instead of o-rings. I
believe those pumps only use one type of bolts. Are the pumps different for
the o-ring vs. crush washer systems? The reason I ask is because the pump
doesn't have a tag on it.
Thanks for any advice.


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